Things to do with your Earth-Moon model:
Activity No. 1:
Have an eclipse!
1. For this activity, you will need your
Earth-Moon model, and another marble
glued to the eraser end of a pencil to
represent the Sun. We use a marble for
both the Moon and Sun because the
two objects appear to be the same size
in our sky.
2. The person who holds the Earth is
the observer. The person who holds the
Sun stands 6 feet beyond the Moon and
tries to hold the Sun model as still as
possible.
3. The person who holds the Moon
tries to move the moon-marble
smoothly so that it passes exactly in
front of the Sun allowing the Earth
observer to see an “eclipse.” The Earth
observer is allowed to give directions
— “a little higher”, “too low”, etc.
4. Let groups of three try this activity.
How many tries will it take your team
to make an eclipse where the Moon
model completely blocks out the Sun
model?
What do we learn?
• The Moon’s orbit is tilted a bit (just 5
degrees.) This small tilt means that the
Moon is usually a little above or below
the Sun as seen from here on Earth –
that makes eclipses very rare!
• The Moon’s orbit carries it in front of
the Sun, blocking out the light during
an eclipse. Many people think that the
Sun moves behind the Moon. In fact,
this is not true. It is the Moon’s orbital
motion that carries it in front of the Sun
during an eclipse.
• An eclipse is very brief. Because the
Moon and Sun both appear quite small
from Earth (about ½ degree wide) the
eclipse does not last very long. The Sun
is blocked for just 2-3 minutes during
most eclipses!
Activity No. 2
The Moon’s Orbit in Motion
1. On a paved area outside, have one
Math it up!
1. The Moon’s diameter is 3,475 km.
The Sun is 1,390,000 km – about 400
times larger. How can the Sun and
the Moon appear to be the same size
in our sky?
2. The Moon is about 385,000 km
away from the Earth (this is the orbital
radius). What is the circumference of
the Moon’s orbit?
3. If the Moon orbits the Earth in
about 28 days, what is its average
speed in orbit?
See the solutions at the bottom of
the